The present invention relates to improvements in the control of heating and cooling measurements of a thermal analysis apparatus used for analyzing temperature dependencies of physical characteristics of materials.
There are various types of conventional temperature control systems or methods, such as those using the following mechanisms: (1) while circulating liquified coolant around a sample chamber to cool the same, the sample chamber is heated by means of a heater disposed within the sample chamber to thereby control the sample chamber temperature; (2) while introducing liquified coolant directly into a sample chamber to cool the same, the sample chamber is heated by means of a heater disposed around the sample chamber to thereby control the sample chamber temperature; and (3) while introducing into a sample chamber gas cooled by liquified coolant to cool the sample chamber, the sample chamber is heated by means of a heater disposed within the sample chamber to thereby control the sample chamber temperature.
While, with the above-mentioned approaches, the heating of the sample chamber by means of the heater does not cause any problem in any of the conventional systems, there have been the following problems with respect to the cooling of the sample chamber. With regard to conventional system (1), since the interior of the sample chamber is not directly cooled but the outer periphery thereof is cooled, the cooling capacity of the coolant source is not sufficient when the sample chamber is not completely insulated, thereby considerably restricting the design of the thermal analysis device. With regard to conventional system (2), while sufficient cooling capacity can be obtained, the balance between cooling and heating by means of the heaters is difficult to control, thereby causing the drawback that the temperature control of the sample chamber cannot be accurately effected. With regard to conventional system (3), since the utilized gas is required to have a boiling point lower than that of the liquified coolant, costly materials are necessary. Moreover, moisture contained in the gas freezes to cause problems such as blockage of gas flow paths.